fix(adminui): stale-open guards, validation summaries, key-delete confirm, error boundary (#604)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DriverConfigModal.razor

@@ -129,20 +129,27 @@
     private string? _saveError;
     private bool _openHandled;
 
+    // Bumped on every open and close; LoadAsync re-checks it after each await so a superseded open can't
+    // install one target's fields under another target's displayed modal (RawBrowseModal idiom).
+    private int _openGeneration;
+
+    private bool IsStale(int generation) => generation != _openGeneration || !Visible;
+
     protected override async Task OnParametersSetAsync()
     {
         if (Visible && !_openHandled)
         {
             _openHandled = true;
-            await LoadAsync();
+            await LoadAsync(++_openGeneration);
         }
         else if (!Visible)
         {
             _openHandled = false;
+            _openGeneration++;
         }
     }
 
-    private async Task LoadAsync()
+    private async Task LoadAsync(int generation)
     {
         _busy = false; _loadError = null; _saveError = null;
         _isNew = string.IsNullOrEmpty(DriverInstanceId);
@@ -158,6 +165,7 @@
         else
         {
             var dto = await Svc.LoadDriverForEditAsync(DriverInstanceId!);
+            if (IsStale(generation)) { return; }
             if (dto is null) { _loadError = $"Driver '{DriverInstanceId}' was not found."; return; }
             _driverType = dto.DriverType;
             _name = dto.Name;
@@ -206,6 +214,7 @@
     {
         Visible = value;
         _openHandled = value;
+        _openGeneration++;
         await VisibleChanged.InvokeAsync(value);
     }
 }